"Caustic cleaning of SS dryers"

Question:

"We have several oil heated (200-300C) 316 and 304 SS pressure vessels at our facility. We are interested in finding out if we can clean them using hot caustic without damaging our dryers. Bearing in mind that once or twice a year these reactors need to be welded on to repair oil leaks in the stainless steel lines and the shell. Cleaning will be done approximately once per week at the most. The vessels (dryers, reactors) are cleaned using a 40% sodium hydroxide solution. the temperature is approx. 80 degrees C and the cleaning takes 24 - 48 hrs. After time has elapsed the vessel walls are rinsed with tap water to remove any remaining contaminants and caustic caught in the cracks and crevices before returning to service."

Answer:

Type 304SS and 316SS should be resistant to 40% sodium hydroxide at 80C, based on both general corrosion and stress corrosion cracking. For additional information on alloy resistance to caustics, please browse our technical newsletter on "Caustic Corrosion" at our "Reference" page on this site.

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